Conventionally, this type of electrochemical devices are generally divided into surface mounting type (square type), coin type, thin type, and cylinder type. A surface mounting electrochemical device is provided, on its mounting surface, with a first terminal and a second terminal having opposite polarities. The surface mounting electrochemical device is surface mountable to a circuit board, similar to surface mounting components such as chip capacitors and chip inductors; therefore, this device is frequently used and is in increased demand.
As disclosed in Japanese Patent Application Publication No. 2010-186691 (Patent Literature 1), a conventional surface mounting electrochemical device comprises a container, a rechargeable electric storage element and electrolyte enclosed in the container, and a first terminal and a second terminal having opposite polarities disposed on the bottom surface of the container, the bottom surface providing a mounting surface.
The container comprises an insulating component having a recess and a metal component to open the recess of the insulating component. The insulating component is formed of ceramics, and the metal component is formed of kovar (a Fe—Ni—Co alloy). A welding ring formed of kovar is disposed on the insulating component such that it encompasses the opening of the recess, so as to connect the metal component with the insulating component. The metal component closes the opening of the recess of the insulating component by being welt to the welding ring. Further, the insulating component is provided with wiring for the first terminal and wiring for the second terminal so as to electrically couple the first terminal to a first electrode of the electric storage element and the second terminal to a second electrode thereof.
Thus, a conventional electrochemical device requires a welding ring, wiring for a first terminal, and wiring for a second terminal on an insulating component constituting a container. Therefore, production cost of the container, particularly the insulating component, is high. It is difficult to lower the production cost or selling price of the electrochemical device.
It has been an important technological issue for manufacturers to produce an electrochemical device having a structure that lowers the selling price.